Officers from the St Louis County Police Department and the Missouri Highway Patrol process demonstrators from the “Black Lives Matter” movement, who had been arrested for protesting on Interstate 70, in Earth City, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

Officers from the St Louis County Police Department process demonstrators from the “Black Lives Matter” movement who had been arrested for protesting on Interstate 70 in Earth City, Missouri, August 10, 2015. Dozens of protesters were arrested on Monday afternoon after blocking rush-hour traffic on Interstate 70 a few miles (km) from Ferguson, Missouri, during demonstrations over the police shooting of an unarmed black man a year ago, according to a Reuters witness. (Photo by Lucas Jackson/Reuters)

Officers from the St Louis County Police Department and the Missouri Highway Patrol process demonstrators from the “Black Lives Matter” movement who had been arrested for protesting on Interstate 70 in Earth City, Missouri, August 10, 2015. (Photo by Lucas Jackson/Reuters)

Officers from the St Louis County Police Department and the Missouri Highway Patrol process demonstrators from the “Black Lives Matter” movement who had been arrested for protesting on Interstate 70 in Earth City, Missouri, August 10, 2015. (Photo by Lucas Jackson/Reuters)

Officers from the St Louis County Police Department and the Missouri Highway Patrol process demonstrators from the “Black Lives Matter” movement who had been arrested for protesting on Interstate 70 in Earth City, Missouri, August 10, 2015. (Photo by Lucas Jackson/Reuters)

An anti-police demonstrator marches in protest in Ferguson, Missouri August 10, 2015. Police in riot gear clashed with protesters who had gathered in the streets of Ferguson early on Tuesday to mark the anniversary of the police shooting of an unarmed black teen whose death sparked a national outcry over race relations. (Photo by Lucas Jackson/Reuters)

St Louis County police officers arrest an anti-police demonstrator in Ferguson, Missouri August 11, 2015. (Photo by Lucas Jackson/Reuters)

St Louis County police officers arrest an anti-police demonstrator in Ferguson, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

St Louis County police officers arrest an anti-police demonstrator in Ferguson, Missouri August 11, 2015. (Photo by Lucas Jackson/Reuters)

Anti-police demonstrators scream as they march in protest in Ferguson, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

St Louis County police officers arrest an anti-police demonstrator in Ferguson, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

An anti-police demonstrator marches in protest in Ferguson, Missouri August 11, 2015. (Photo by Lucas Jackson/Reuters)

St Louis County police officers interact with anti-police demonstrators during protests in Ferguson, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

St Louis County police officers interact with anti-police demonstrators during protests in Ferguson, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

St Louis County police officers watch as anti-police demonstrators march in protest in Ferguson, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

Onlookers watch as anti-police demonstrators march in protest in Ferguson, Missouri August 10, 2015. (Photo by Lucas Jackson/Reuters)

Members of the Oath Keepers walk with their personal weapons on the street during protests in Ferguson, Missouri August 11, 2015. (Photo by Lucas Jackson/Reuters)

An anti-police demonstrators screams at a St Louis County police officers during protests in Ferguson, Missouri August 11, 2015. (Photo by Lucas Jackson/Reuters)

Two anti-police demonstrators walk away from a line of St Louis County police officers during protests in Ferguson, Missouri August 11, 2015. (Photo by Lucas Jackson/Reuters)

Police hold a protester who was detained in Ferguson, Missouri, August 10, 2015. Protesters regrouped in Ferguson, Missouri, on Monday evening after a state of emergency was declared, aimed at preventing a repeat of violence the night before on the anniversary of the police shooting of unarmed black man Michael Brown. (Photo by Rick Wilking/Reuters)

Police hold a protester who was detained in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

Police hold a protester who was detained in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

Police detain a protester in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

A police officer holds his weapon as a protester is detained (rear) in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

Police ask protesters to stay off the street in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

A police officer holds a protester who was detained in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

Protesters hold up signs on top of a closed business in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

Police take a mug shot of a protester who was detained in Ferguson, Missouri, August 10, 2015. (Photo by Rick Wilking/Reuters)

Protesters walk on the street, Monday, August 10, 2015, in Ferguson, Mo. Ferguson was a community on edge again Monday, a day after a protest marking the anniversary of Michael Brown's death was punctuated with gunshots. (Photo by Jeff Roberson/AP Photo)

An officer holds a flag he took from a protestor, Monday, August 10, 2015, in Ferguson, Mo. (Photo by Jeff Roberson/AP Photo)

Officers arrest a protester, Monday, August 10, 2015, in Ferguson, Mo. (Photo by Jeff Roberson/AP Photo)

St. Louis County Police make an arrest along West Florissant Avenue, Monday, August 10, 2015, in Ferguson, Mo. (Photo by Jeff Roberson/AP Photo)

Police patrol on Monday, August 10, 2015, in Ferguson, Mo. (Photo by Jeff Roberson/AP Photo)